You have to open your browser (on server console or during a remote session) using “Run as Administrator”.
Then go to http://localhost/Reports (NOTE: do not put http:///Reports – it doesn’t work).
Go to Folder Settings and assign role browser and content manager to your administrator account. It should start working now.
If you are running it on Windows server 2008 don’t forget to create inbound rule in windows firewall to port 80.